[Mlir-commits] [mlir] [mlir][acc] Erase empty kernel_environment ops during canonicalization (PR #166633)

[Razvan Lupusoru]

================
@@ -1042,6 +1042,35 @@ struct RemoveConstantIfConditionWithRegion : public OpRewritePattern<OpTy> {
   }
 };
 
+/// Remove empty acc.kernel_environment operations. If the operation has wait
+/// operands, create a acc.wait operation to preserve synchronization.
+struct RemoveEmptyKernelEnvironment
+    : public OpRewritePattern<acc::KernelEnvironmentOp> {
+  using OpRewritePattern<acc::KernelEnvironmentOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(acc::KernelEnvironmentOp op,
+                                PatternRewriter &rewriter) const override {
+    assert(op->getNumRegions() == 1 && "expected op to have one region");
+
+    Block &block = op.getRegion().front();
+    if (!block.empty())
+      return failure();
+
+    // Remove empty kernel environment
+    // preserve synchronization by creating acc.wait operation if needed
+    if (!op.getWaitOperands().empty())
----------------
razvanlupusoru wrote:

The acc.kernel_environment has all of the following wait operands:
```
    Variadic<IntOrIndex>:$waitOperands,
    OptionalAttr<DenseI32ArrayAttr>:$waitOperandsSegments,
    OptionalAttr<DeviceTypeArrayAttr>:$waitOperandsDeviceType,
    OptionalAttr<BoolArrayAttr>:$hasWaitDevnum,
    OptionalAttr<DeviceTypeArrayAttr>:$waitOnly);
```

Seems your logic here is only handling one of them.

https://github.com/llvm/llvm-project/pull/166633